U.S. patent application number 12/143583 was filed with the patent office on 2008-12-25 for control device for a washing machine.
This patent application is currently assigned to COPRECITEC, S.L.. Invention is credited to Rodrigo Orue Orue, Fernando Sales Villalabeitia.
Application Number | 20080314090 12/143583 |
Document ID | / |
Family ID | 38556627 |
Filed Date | 2008-12-25 |
United States Patent
Application |
20080314090 |
Kind Code |
A1 |
Orue Orue; Rodrigo ; et
al. |
December 25, 2008 |
Control device for a washing machine
Abstract
A device and method for controlling a drainage pump of a washing
machine. The drainage pump is powered by a synchronous motor that
is connected to a mains voltage bus by a switch. During one or more
stages of a washing program the switch is operated to apply in each
half cycle of the mains voltage a delay time from the zero setting
of the mains voltage to cause the motor to operate in a cut-wave
mode.
Inventors: |
Orue Orue; Rodrigo;
(Vitoria-Gasteiz (Alava), ES) ; Sales Villalabeitia;
Fernando; (Mondragon (Gipuzkoa), ES) |
Correspondence
Address: |
BERENBAUM, WEINSHIENK & EASON, P.C
370 17TH STREET, SUITE 4800
DENVER
CO
80202
US
|
Assignee: |
COPRECITEC, S.L.
Aretxabaleta (Gipuzkoa)
ES
|
Family ID: |
38556627 |
Appl. No.: |
12/143583 |
Filed: |
June 20, 2008 |
Current U.S.
Class: |
68/12.16 |
Current CPC
Class: |
D06F 39/083 20130101;
D06F 2204/084 20130101 |
Class at
Publication: |
68/12.16 |
International
Class: |
D06F 33/02 20060101
D06F033/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 21, 2007 |
ES |
U200701334 |
Claims
1. A washing machine comprising: a drum rotatable by a main motor
in accordance with a speed order corresponding to various stages of
a washing program; and a drainage pump to drain water from the
drum, the drainage pump driven by a synchronous motor that is
powered by a mains voltage bus, the mains voltage comprising a
plurality of half cycles, the discharge motor controlled by a first
switch in the mains voltage bus, the switch operable to apply in
each half cycle of the mains voltage a delay time from the zero
setting of the mains voltage to cause the motor to operate in a
cut-wave mode.
2. A washing machine according to claim 1 wherein the drainage pump
operates in a cut-wave mode during a first stage of the washing
program.
3. A washing machine according to claim 2 wherein the first stage
is a centrifugation stage.
4. A washing machine according to claim 2 wherein the first stage
is determined by a water level in the drum.
5. A washing machine according to claim 1 wherein the first switch
is operable to supply full mains voltage to the synchronous motor
to cause the motor to operate in a full-wave mode.
6. A washing machine according to claim 5 wherein the motor
operates in full-wave mode at a stage in the washing program
preceding a centrifugation stage.
7. A washing machine according to claim 1 wherein the synchronous
motor is a synchronous permanent-magnet motor.
8. A washing machine according to claim 1 wherein the delay time is
a preset constant time.
9. A washing machine according to claim 1 wherein the main motor is
operably controlled by a second switch in the mains voltage
bus.
10. A washing machine according to claim 9 further comprising a
control device for controlling the first and second switches.
11. A method for controlling a drainage pump in a washing machine,
the drainage pump operated by a synchronous motor that is connected
to a mains voltage bus by a first switch, the mains voltage
comprising half cycles, the method comprising operating the first
switch in the mains voltage bus to apply in each half cycle of the
mains voltage a delay time from the zero setting of the mains
voltage to cause the motor to operate in a cut-wave mode.
12. A method according to claim 11 wherein the washing machine
comprises a drum that is rotated by a main motor in accordance with
a speed order corresponding to various stages of a washing program,
one stage being a centrifugation stage, the centrifugal stage
characterized by an initial increasing drum speed, the synchronous
motor caused to operate in the cut-wave mode when the drum rotation
stops increasing.
13. A method according to claim 11 wherein the washing machine
comprises a drum that is rotated by a main motor in accordance with
a speed order corresponding to various stages of a washing program,
one stage being a centrifugation stage, the synchronous motor
caused to operate in the cut-wave mode during the centrifugation
stage.
14. A method according to claim 12 wherein the synchronous motor is
caused to operate in the cut-wave mode at a waiting time after the
drum rotation stops increasing.
15. A method according to claim 11 wherein the washing machine
comprises a drum that is rotated by a main motor in accordance with
a speed order corresponding to various stages of a washing program,
the synchronous motor caused to operate in the cut-wave mode when a
water level in the drum reaches a preset level.
16. A method according to claim 15 wherein the synchronous motor is
caused to operate in the cut-wave mode at a waiting time after the
water level reaches the preset level.
17. A method according to claim 11 wherein the synchronous motor is
a synchronous permanent-magnet motor.
18. A method according to claim 11 wherein the delay time is a
preset constant time.
19. A method according to claim 11 wherein the main motor is
operably controlled by a second switch in the mains voltage bus.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to Spanish Patent
Application ES-U200701334, filed Jun. 21, 2007.
TECHNICAL FIELD
[0002] The present invention relates to a device for controlling a
domestic washing machine, and more specifically to the control of a
drainage pump of a washing machine.
BACKGROUND
[0003] Known washing machines comprise a drum that is rotated by
means of a main motor in accordance with a speed order
corresponding to the various phases of a washing program selected
by a user, and a drainage pump with a discharge motor to drain the
flow of water that has accumulated in the drum. The main motor is
usually of the universal motor type, with the speed being regulated
by phase control and tachometer feedback. The main motor is
controlled by a control device that acts on a switch, normally a
triac. The time reference that is normally used to carry out the
phase control of the main motor is the zero setting of the mains
voltage.
[0004] The control device also controls the discharge motor of the
drainage pump, using a respective switch, normally a triac, to do
so. The discharge motor is usually a synchronous permanent-magnet
motor and is usually operated, through the triac, by an on-off
control.
[0005] GB 2274343 describes a control device for a washing machine
that controls the discharge motor of the drainage pump. The control
device uses an on-off control to operate the discharge motor, in
other words, the discharge motor is powered in the phases in which
an amount of water has to be drained from the drum, with the
discharge motor not being powered in the phases in which there is
no water.
SUMMARY OF THE DISCLOSURE
[0006] The object of the invention is to provide a control device
for a washing machine as defined in the claims.
[0007] The control device according to the invention is applied in
washing machines which comprise a drum that is rotated by a main
motor in accordance with a speed order corresponding to the various
phases of a washing program selected by a user, and a drainage pump
with a discharge motor to drain the flow of water that has
accumulated in the drum, the discharge motor being a synchronous
permanent-magnet motor.
[0008] The control device according to the invention controls the
main motor and the discharge motor by means of respective switches
through which a mains voltage may be applied to the motors. In
certain phases of the overall washing program the control device
acts on the switch of the discharge motor and applies, in each
half-cycle of the mains voltage, a constant delay time from the
zero setting of the mains voltage.
[0009] As a result, instead of applying an on-off control, as is
the case of the prior art, an alternative method is used, which can
be designated as a cut-wave mode, in which the aforementioned delay
time in each half-cycle of the mains voltage, is applied with the
effect that the effective voltage (or RMS voltage) applied to the
discharge motor is reduced. Thus, in the washing program phases in
which the discharge motor operates virtually without a load, that
is, draining a minimum flow of water mixed with air, it can be
opted for operating the discharge motor in this cut-wave mode,
instead of continuing to power it from the mains voltage in
full-wave mode and thereby waste energy in the process, or of
stopping it altogether, which means that the motor has to be
started again whenever water needs to be drained.
[0010] The supply of a smaller effective voltage to the discharge
motor during certain phases reduces the power consumed by the
discharge motor and thus prolongs the useful life of the discharge
motor. Furthermore, by preventing the discharge motor from being
powered by the mains voltage in the phases in which there is hardly
any load, the vibrations and changes of speed resulting from the
acceleration and deceleration of the rotor in the phase are
reduced. In addition, the fact that the discharge motor is not
continually being switched on, the discharge motor remaining in
cut-wave mode instead of having to be switched off altogether,
prevents sudden mechanical stresses caused by starting up this type
of motor.
[0011] Given that the time reference that is normally used to
control the main motor phase is the zero setting of the mains
voltage, the control device already knows the zero setting points
of the mains voltage. This makes it very easy to implement the
invention in the control devices in the prior art, as all that
needs to be done is set the value of the delay time to be applied,
determine the phases corresponding to each washing program in which
the cut-wave mode will be used, and apply the delay time based on
the zero settings of the mains voltage (which are already known) in
the phases. In practice, this merely involves using a timer to set
the delay and adding an additional program to the control algorithm
of the drainage pump.
[0012] As the delay time may be a preset constant and as the delay
time is applied in accordance with the scheduled load (which
depends on the phase of the washing program), it is not necessary
to fit any additional sensor. In alternative embodiments, the delay
time is not a constant but is variable.
[0013] These and other advantages and characteristics of the
invention will be made evident in the light of the drawings and the
detailed description thereof.
BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Preferred embodiments of the present disclosure are
described herein with reference to the drawings wherein:
[0015] FIG. 1 shows a block diagram of a control device in one
implementation.
[0016] FIG. 2 shows a graph showing the mains voltage and the
current powering the discharge motor when it is operating in
full-wave mode.
[0017] FIG. 3 shows a graph showing the mains voltage and the
current powering the discharge motor when it is operating in
cut-wave mode.
[0018] FIG. 4 shows an example of the various phases of a washing
program, detailing the phases in which the discharge motor operates
in full-wave mode and the phases in which it operates in cut-wave
mode.
DETAILED DESCRIPTION
[0019] The inventive control device 1 controls a main motor 2 that
rotates a drum (not shown in the figures) in accordance with a
speed order corresponding to the various phases of a washing
program selected by a user, and also controls a discharge motor 3
of a drainage pump (not shown in the figures) in order to drain a
flow of water that has accumulated in the drum, the discharge motor
3 being a synchronous motor. In one embodiment, the discharge motor
3 being a synchronous permanent-magnet motor.
[0020] As shown in the diagram in FIG. 1, the control device 1
controls the main motor by means of a switch 4 and controls the
discharge motor 3 by means of a switch 5. Through the switches 4
and 5 located in the mains voltage bus, a mains voltage Vr may be
applied to the main motor 1 and to the discharge motor 3
respectively. In a preferred embodiment the switches 4 and 5 are
triacs.
[0021] Usually, the discharge motor 3 is operated by an on-off
control, in other words, when "on" the mains voltage is applied to
it and it thus operates in full-wave mode. Alternatively, when
"off" no voltage is applied to it at all, as a result of which the
discharge motor 3 stops. In certain phases of the washing program,
specifically in the phases in which the water is not drained or the
amount drained is minimal, the control device 1 according to the
invention acts on the switch 5 of the discharge motor 3 and
applies, in each half-cycle of the mains voltage Vr, a constant
delay time Tr from the zero setting of the mains voltage Vr,
causing the discharge motor 3 to operate in cut-wave mode.
[0022] When the control device 1 causes the drainage motor 3 to
operate in full-wave mode, the switch 5 allows an uninterrupted
passage of current and the current that is applied to the discharge
motor 3 is the current shown in FIG. 2, which is a sinusoidal
current with a specific delay in relation to the mains voltage due
to the impedance of the discharge motor 3, to its rotor and its
mechanical load, to the working point in the application and to the
value of the actual frequency and the value of the voltage.
[0023] When the control device 1 causes the discharge motor 3 to
operate in cut-wave mode, it includes the delay times Tr, with the
result that the current applied to the discharge motor 3 is a
current like that shown in FIG. 3. It can be seen that when
applying the delay time Tr the wave amplitude .DELTA.I of the
current in the discharge motor is smaller than the wave amplitude
.DELTA.Io in full-wave mode, with the result that the power
consumed by the motor 3 in this cut-wave mode is less than the
power consumed in full-wave mode. In addition, given that the
leakage in the copper of the discharge motor 3 is proportional to
the square of the current, the leakage is also reduced as well as
the leakage in the iron, thus extending the useful life of the
discharge motor 3.
[0024] A value below a critical time is chosen for the delay time
Tr, this value being the delay time from which the voltage supplied
to the discharge motor 3 is not sufficient for it to maintain the
rotor speed in synchronism with the rotating magnetic field of the
stator. The synchronism leakage voltage basically depends on the
constructive characteristics of the discharge motor, the hydraulic
load, the frequency of the mains voltage and the value of the mains
voltage. To ensure that the discharge motor 3 does not stop when
operating in cut-wave mode, a safety margin is established between
the critical time and the selected delay time Tr.
[0025] At all times, the control device 1 knows the phase in which
the washing program is found and may therefore cause the discharge
motor 3 to work in the most appropriate mode in each phase. The
operating of the discharge motor 3 can be optimised by causing it
to switch to the cut-wave mode in the phases in which the flow of
water required from the pump is minimal.
[0026] Thus, during the centrifugation stage in the phases in which
the flow of water is predicted to be minimal, the discharge motor 3
operates in cut-wave mode. The phases in which the flow is minimal
are those following the phases in which there is a continual
increase in the speed order of the drum rotation. When the speed
order increases water must be drained, and therefore full-wave mode
is used, but by the time the speed order stops increasing, most of
the water has already been drained, as a result of which the
control device 1 may operate the discharge motor 3 in cut-wave
mode, with the delay time Tr therefore being applied.
[0027] In a preferred embodiment, the control device 1 introduces a
waiting time before beginning to apply the delay time Tr, from the
moment at which the speed order of the drum rotation stops
increasing.
[0028] Furthermore, in the washing stage, which precedes the
centrifugation stage, discharge stages are included and in which
the discharge motor 3 has to operate in full-wave mode. When the
discharge stages are about to conclude, more specifically after the
level of water that has accumulated in the drum reaches a preset
level H, the control device 1 may begin to apply the delay time
Tr.
[0029] In a preferred embodiment, the control device 1 introduces a
waiting time before beginning to apply the delay time Tr, from the
moment at which the level of water of the drum reaches the level H
during the washing stage.
[0030] During the washing stage, there is also option of causing
the discharge motor 3 to function with the on-off control, the use
of the half-wave mode being reserved solely for the centrifugation
stage. In such an event, the discharge motor 3 begins the
centrifugation stage by operating in full-wave mode in order to
ensure the discharge motor 3 starts.
[0031] FIG. 4 shows an example of a washing program in which the
flow of water Q displaced by the discharge motor 3 during the
program is shown. A continuous line is used to indicate the phases
in which the full-wave mode is used and a broken line is used to
indicate the phases in which the cut-wave mode is used. It can be
seen that the cut-wave mode is used in the phases in which the flow
of water that has accumulated is minimal.
* * * * *